<?php 
class C
{	
	private static $_instance = null;

    protected $_options = array(
        'file_name_prefix' => 'cache__',
    	'mode'            => 1, //mode 1 为serialize model 2为保存为可执行文件
    );
    
    public function __construct(){
        $this->_options['cache_dir'] = ROOT.'/runtime/cache/';
    	!file_exists($this->_options['cache_dir']) && xmkdir($this->_options['cache_dir']);
    }
	
	/**
	 * 得到本类实例
	 * 
	 * @return Ambiguous
	 */
	public static function getInstance()
	{
		if(self::$_instance === null)
		{
			self::$_instance = new self();
		}
		return self::$_instance;
	} 
	
	/**
	 * 得到缓存信息
	 * 
	 * @param string $id
	 * @return boolean|array
	 */
	public static function get($id)
	{
		$instance = self::getInstance();
		
		//缓存文件不存在
		if(!$instance->has($id))
		{
			return false;
		}
		
		$file = $instance->_file($id);
		
		$data = $instance->_fileGetContents($file);
		
		if($data['expire'] == 0 || time() < $data['expire'])
		{
			return $data['contents'];
		}
		return false;
	}
	
	/**
	 * 设置一个缓存
	 * 
	 * @param string $id   缓存id
	 * @param array  $data 缓存内容
	 * @param int    $cacheLife 缓存生命 默认为0无限生命
	 */
	public static function set($id, $data, $cacheLife = 0)
	{
		$instance = self::getInstance();
		
		$time = time();
		$cache 		   = array();
		$cache['contents'] = $data;
		$cache['expire']   = $cacheLife === 0 ? 0 : $time + $cacheLife;
		$cache['mtime']    = $time;
		
		$file = $instance->_file($id);
		
		return $instance->_filePutContents($file, $cache);
	}
	
    /**
     * 清除一条缓存
     * 
     * @param string cache id	 
     * @return void
     */   
	public static function delete($id)
	{
		$instance = self::getInstance();
		
		if(!$instance->has($id))
		{
			return false;
		}
    	$file = $instance->_file($id);
    	//删除该缓存
    	return unlink($file);
	}
	
	/**
	 * 判断缓存是否存在
	 * 
	 * @param string $id cache_id
	 * @return boolean true 缓存存在 false 缓存不存在
	 */
	public static function has($id)
	{
		$instance = self::getInstance();
		$file     = $instance->_file($id);
		
		if(!is_file($file))
		{
			return false;
		}
		return true;
	}
	
	/**
	 * 通过缓存id得到缓存信息路径
	 * @param string $id
	 * @return string 缓存文件路径
	 */
	protected function _file($id)
	{
		$instance  = self::getInstance();
		$fileNmae  = $instance->_idToFileName($id);
		return $instance->_options['cache_dir'] . $fileNmae;
	}	
	
	/**
	 * 通过id得到缓存信息存储文件名
	 * 
	 * @param  $id
	 * @return string 缓存文件名
	 */
	protected function _idToFileName($id)
	{
		$instance  = self::getInstance();
		$prefix    = $instance->_options['file_name_prefix'];
		return $prefix . '___' . $id;
	}
	
	/**
	 * 通过filename得到缓存id
	 * 
	 * @param  $id
	 * @return string 缓存id
	 */
	protected function _fileNameToId($fileName)
	{
		$instance  = self::getInstance();
		$prefix    = $instance->_options['file_name_prefix'];
		return preg_replace('/^' . $prefix . '___(.*)$/', '$1', $fileName);
	}
	
	/**
	 * 把数据写入文件
	 * 
	 * @param string $file 文件名称
	 * @param array  $contents 数据内容
	 * @return bool 
	 */
	protected function _filePutContents($file, $contents)
	{
		if($this->_options['mode'] == 1)
		{
			$contents = serialize($contents);
		}
		else 
		{
			$time = time();	
	        $contents = "<?php\n".
	                " // mktime: ". $time. "\n".
	                " return ".
	                var_export($contents, true).
	                "\n?>";
		}
		
		$result = false;
	    $f = @fopen($file, 'w');
        if ($f) {
            @flock($f, LOCK_EX);
            fseek($f, 0);
            ftruncate($f, 0);
            $tmp = @fwrite($f, $contents);
            if (!($tmp === false)) {
                $result = true;
            }
            @fclose($f);
        }
		@chmod($file,0777);
		return $result;				
	}
	
	/**
	 * 从文件得到数据
	 * 
	 * @param  sring $file
	 * @return boolean|array
	 */
	protected function _fileGetContents($file)
	{
		if(!is_file($file))
		{
			return false;
		}
		
		if($this->_options['mode'] == 1)
		{
			$f = @fopen($file, 'r'); 
			@$data = fread($f,filesize($file));
			@fclose($f);
			return unserialize($data);
		}
		else
		{
			return include $file;
		}
	}
	
	/**
	 * 设置缓存路径
	 * 
	 * @param string $path
	 * @return self
	 */
	public static function setCacheDir($path)
	{
		$instance  = self::getInstance();
        if (!is_dir($path)) {
            exit('file_cache: ' . $path.' 不是一个有效路径 ');
        }
        if (!is_writable($path)) {
            exit('file_cache: 路径 "'.$path.'" 不可写');
        }
    
        $path = rtrim($path,'/') . '/';
        $instance->_options['cache_dir'] = $path;
        
        return $instance;
	}
	
	/**
	 * 设置缓存文件前缀
	 * 
	 * @param srting $prefix
	 * @return self
	 */
	public static function setCachePrefix($prefix)
	{
		$instance  = self::getInstance();
		$instance->_options['file_name_prefix'] = $prefix;
		return $instance;
	}
	
	/**
	 * 设置缓存存储类型
	 * 
	 * @param int $mode
	 * @return self
	 */
	public static function setCacheMode($mode = 1)
	{
		$instance  = self::getInstance();
		if($mode == 1)
		{
			$instance->_options['mode'] = 1;
		}
		else
		{
			$instance->_options['mode'] = 2;
		}
		
		return $instance;
	}
	
	/**
	 * 删除所有缓存
	 * @return boolean
	 */
	public static function flush()
	{
		$instance  = self::getInstance();
		$glob = @glob($instance->_options['cache_dir'] . $instance->_options['file_name_prefix'] . '__*');
		
		if(empty($glob))
		{
			return false;
		}
		
		foreach ($glob as $v)
		{
			$fileName = basename($v);
			$id =  $instance->_fileNameToId($fileName);
			$instance->delete($id);
		}
		return true;
	}
}

